Are you the ones filling the nets, or do you have help? How many horses is this for, and are they sharing nets or would this be for stalls only? What is your reason for providing the nets? Is it to offer more hay but keep things clean/tidy? Is it to slow down consumption of hay, something else?
All of those questions would change my answer for which is most suitable.
As someone who keeps their horses at home, I love my hay net (HayChix round bale net + HayChix square bale net)… BUT… As someone who has worked in barns the first 20 years of their horse-life, I despise hay nets. NibbleNets were my least favorite as a worker - they may have changed their design in the last ten years but the openings were shallow and difficult to get much more than a flake into. I worked at a 40 stall barn that had the entire yard in hay nets… It was a nightmare and took two hours to collect all the hay nets, fill them, disburse them back to their stalls and paddocks. Lots of trips back and forth too. Don’t discount the labor costs associated with hay nets.
Any net will add more labor to your barn staff’s routine, so if you are operating a larger boarding barn keep in mind that a standard hay net (2 flakes) doesn’t keep a horse busy for long and it’ll be a full time job for staff to be constantly replenishing the bag if your MO is genuine free choice hay. Bigger bags are not always better either - they can be a PITA to hang up and move around, most younger workers can’t hang a bale easily chest height or higher, and they present a few more risks of a shoe or blanket being caught in them when they get empty and hang down.
There’s also the training-the-staff considerations: horses with shoes and/or blankets should not be near any nylon string nets. Never ever on the ground, either. Any net should be horse’s chest height or higher - we hang so the net is level with their withers. Horses can and will find ways to get caught in their nets. I once had a horse get three of his shoes stuck in his NibbleNet. We couldn’t free him from the net because he was standing on top of it, he couldn’t free himself because the nylon was too strong. I ended up cutting the bag open with shears which was not a delicate task. Horse was okay with some banamine but very sore for a few days.
Getting into the safety features, I think my preference when taking safety of boarders into consideration, plus needs of horse, plus convenience needs of workers, is the large Kensington Hay Bags that can fit half to a whole bale in them. Their backs are made of the same material as blankets, with cotton/nylon string along the front. They can be hung up on the side of fences or the side of the stall chest height or higher, and have large enough slots for easy access without total wastage.
One of our horses is separated from the herd and I use these:
They are easy to stuff hay into and just keep hay above the ground - they don’t necessarily restrict intake (which I like) but they won’t prevent a messy eater from being messy, either.
Coming from the perspective as a barn grunt, I think the Kensington or a standard large cotton rope hay net are really the easiest/most convenient for staff.
I am so glad, as a tangent, to have round bales now. I use a Hay Hut + HayChix hay net and see zero waste on a 600lb bale that six horses eat from. I wish I bought the HayChix net sooner.